PC Smoke Chapter 2

So, after the long discussion on smoke detectors I thought it best to start a new post hole.

I opened the case and looked at the board. It is a so called military grade MSI ATX motherboard. I saw no charred anything. But I did see pieces of charred something sitting on the board and looked upwards and discovered a cable hanging loose.

Look closely at the end of the cable and saw what was left of a drive power connector. Traced that to the power input to a Hitachi 2T HDD.

What that my C: drive (Win 7) ? Yikes! I have four 2T drives in there. Thank goodness I just backed up the C: drive using Macrium Reflect Free to an external USB Drive.

Anyway, now I am wondering if the power supply was taken out. It is a 600W CoolerMaster RS-500-PCAR. Do these protect themselves or just melt down with the connector. The cabling is hard ot get to since the PC is packed tight with 4 HHD and two DVDs and a few boards plugged into the motherboard.

So maybe the connector contact was not so good and the resistance increased to a point where the connector melted the shorted out? The connector was melted AND also turned to dust.

Connector went bad or ?

Wonder if the drive is still good. Got to take it out and have a good look.

Thoughts (other than smoke detectors).

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Reply to
OG
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I would not trust the connectors now.

That means replacing the power supply.

If, on the other hand, the connector was a SATA Y-cable or a SATA extension, maybe that was the defective part, and the power supply doesn't have a quality issue.

If the power supply connector end burned, you cannot use that drive again. The contacts on the drive end, will be heat-damaged and degraded, and will encourage the connector on a new supply, to fail in exactly the same way. You may be able to connect the drive long enough to clone it, but I would no longer trust it.

When the connector is new, the metal is nice and shiny and conductive. After an overheat issue, the metal is oxidized, heat stressed, and has a higher resistance. Replacing both ends of the connector system, is required to return things to mint condition. And that's why you shouldn't use that hard drive again.

If you do want to use the hard drive again, you can use an extension cord. When it burns the extension cord, there would be no damage to the new power supply.

PSU ----- Molex to SATA ---- ---- - - - Bad drive

^ | +--- Will burn here...

So if it were to burn again, just the middle (extension cable) would need to be replaced. It all depends on whether you like the smell of "resistor smoke", as to whether that is a practical alternative (isolates the damage a bit better). The second time it fails, will be for potentially different reasons than the first time, due to the heat damage to the drive end power contacts.

You can easily solder a pigtail to the hard drive, to power it in place of the SATA 15 pin. So even if you didn't have backups, you may be able to get the data off it. It would require locating where

+5V, +12V, GND, GND are on the controller board, to tap in and connect a Molex pig tail as a replacement. I did that to replace a burned end connector on a video card and it held up fine.

*******

One suggestion here is "tin whiskers". A metallurgy problem. You cannot use pure tin on assemblies, because a thin spike of material will "grow" between conductors. The whisker grows between conductors, until it shorts them out.

formatting link

We had some special RAM modules we designed at work. The first ones, were made with gold all over the place. At the time, gold wasn't nearly as expensive as it is now. Anyway, in the spirit of cost-reduction, the next generation (same form factor), they decided it would be fun to make them with tin in place of the gold. And apparently, the person who did that, had never heard of tin whiskers. And pretty well exactly one year to the day, each module would fail, as a whisker would grow across the surface of the substrate. We used to run an Xacto knife between tracks, to cut the whiskers, but they would only grow back again. Making the RAM modules a write-off. The substrate in this case was ceramic, so these were not even remotely close to modern DIMMs or SIMMs in design. A thorough understanding of metallurgy is required for anyone doing this sort of design work (i.e. don't ask me to do it :-) )

Metallurgy affects lots of stuff. When you see electrical contacts on things, they consist of a number of layers of plating. The materials and order of layering is determined by safe metallurgy. So you could use tin, if it was combined with the correct other materials. So someone knows what metal mixture, plate up, or whatever, will stop whiskers. There's no need for whiskers in electronics in 2016. This is "all known stuff". You shouldn't be designing connectors and cables, unless you know this stuff.

Paul

Reply to
Paul

What Paul says (+1)

Reply to
hrhofmann

IMO, 600w and cooling is not nearly enough for what you have that machine doing. This machine has a 750w p/s and sometimes it gets stressed.

2-4 hdds, 1-2 dvds, various cards, etc. cpu fan, hdd fan, 2 bridge fans, ram fan, pwr sup fan, gpu fan, all set to max. Everything overclocked. 24" floor fan on the side of the case. When the current p/s goes bad I'll get a 1 kw p/s.
Reply to
Paul in Houston TX

The total power of the supply is irrelevant as to the connector that burned. The supply only delivers what is called for.

More than likely the connector was not pushed in all the way, when the drive was installed.

Otherwise it was loose pins

Reply to
philo

Yea, I agree. Should have made that clear in my post.

Reply to
Paul in Houston TX

At any rate, thought I've seen burned or over-heated connections, I've never seen one go up in smoke.

Reply to
philo

Another possibility is that the drive developed an internal short (maybe blown power fet in the motor drive) and started drawing huge currents. The connector ended up being the weakest link and burned up.

That is one of the dangers of putting insanely overpowered supplies in PCs. Some people have 700+ W supplies in ordinary desktop systems that typically draw less than 150 W. This is mostly due to sellers making a lot of money over-selling stuff to people who don't know better.

Jon

Jon

Reply to
Jon Elson

I have more then once a shorted USB connector is worse:)

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Reply to
Andy

Upon further examination it looks like the connector may have wiggled loose. Why, because the gold connector pads on the HDD were melted off only near the edge of the connector. Little damage to the PWB of the HDD. I see no damage to the gold from that damaged area into the HDD.

A short occurred between the 12v Yellow and GND Black power feed. The connector evaporated there (ash and chunks all over) and the wires evaporated back from where the connector was by over an inch. Yes, over an inch of yellow and black (adjacent) wire evaporated. Must have been exciting to see the arc.

So probably the arc started, the connector evaporated and came off the HDD, the arc continued and ate the wires until the PS gave its all then had enough.

So the smoke was a combination of gold, connector plastic, copper PWB trace, copper wire, vinyl wire covering and whatever else was in the mix. Thankfully I did not get to breath much since the whole house fan and computer room fan were immediately turned on and evacuated the "computer" room quickly.

Got a new PS and HDD ready to install. Will take baby steps putting it all together. The new EVGA PS is much higher efficiency than the last. The new HDD is a WD "Black".

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Reply to
OG

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